Introduction of statcom

objective

Today · changing electric power systems create a growing need for Reliability, flexibility, fast

response and accuracy.

Flexible Alternating Current Transmission Systems are new devices emanating from recent innovative technologies that are maintain altering voltage

phase angle

In power system, real power and reactive power is controlled by the voltage and phase angle difference between the sending end and receiving end respectively. Impedance of the transmission line can also be used to control real and reactive power. Flexible AC Transmission Systems (FACTS) are used to improve the power transfer capability of transmission line.

EXISTING SYSTEM

THYRISTOR CONTROL REACTOR THYRISTOR SWITCHED CAPACITOR STATIC VAR COMPENSATOR THYRISTOR SWITCHED

SERIESCOMPENSATOR STATIC COMPENSATOR SELF COMMUTATED COMPENSATOR UNIFIED POWER FLOW CONTROLLER

Different fact devices

INCREASE THE CAPABILITY OF LOADING OF LINES TO THEIR THERMAL CAPABILITES

INCREASE THE SYSTEM SECURITY THROUGHT RISING THEIR TRANSIENTSTABILITY LIMIT

CONTROL OF POWER FLOW AS ORDERED REDUCE REACTIVE POWER FLOW

Benefits of devices

static synchronous compensator, is a regulating device used on ac current electricity transmission networks. It is based on a power electronics voltage-source converter and can act as either a source or sink of reactive AC power  to an electricity network. If connected to a source of power it can also provide active AC power It is a member of the FACTS family of devices.

Structure of Statcom

STATCOM (Static Synchronous Compensator)

Connection block Diagram

Voltage-Source Converter (VSC) DC Capacitor Inductive Reactance (X) Harmonic Filters

Components of Statcom

Square-wave Inverters using Gate Turn-Off Thyristor

GTO-based STATCOM Simple Diagram

A gate turn-off thyrisistor (GTO) is a special type of thyrisistor, which is a high-power semiconductor device. It was invented at General Electric. GTOs, as opposed to normal thyrisistors are fully controllable switches which can be turned on and off by their third lead, the GATE lead.

What is GTO

Diagrams

CONTINUOUS AND DYNAMIC VOLTAGECONTROL

HIGH EFFICIENCY HIGH DYNAMIC VERY FAST RESPONSE

TIME SINGLE PHASE CONTROL FOR

UNBALANCED LOADS REACTIVE POWER COMPENSATION

Main Advantages

The static synchronous compensator (STATCOM) is increasingly popular in power system application. In general, power factor and stability of the utility system can be improved by STATCOM. Specifically

Why this device is used

Voltage support and controlVoltage fluctuation and flicker mitigationUnsymmetrical load balancingPower factor correctionActive harmonics cancellationImprove transient stability of the power system

Continue….!

The STATCOM has the ability to provide more capacitive reactive power during faults, or when the system voltage drops abnormally, compared to ordinary static var compensator. This is because the maximum capacitive reactive power generated by a STATCOM decreases linearly with system voltage, while that of the SVC is proportional to the square of the voltage. Also, the STATCOM has a faster response as it has no time delay associated with thyristor firing.

Statcom vs. SVC

Phase diagram

When operating as a pure STATCOM (without losses or SMES attached) the generated voltage is exactly in phase with the AC system voltage. If the generated voltage is greater that the terminal voltage then the device will supply VARs (i.e. is capacitive) to the system. If the internal voltage is less than the terminal voltage, the device will absorb VARS (i.e. is inductive) from the system. The control system of the STATCOM is extremely fast and therefore can rapidly change the magnitude (and phase) of the electronically generated voltage.

System of Statcom

Diagram

Ultra dynamic response (<10ms) No steps Ind. + cap. Capabilities Low harmonics no filters required Cheaper than SVC below §50MVAR

Characteristics of Statcom